Inghouse electric



Aug. 25, 1925.

C LE G. FORTESCUE NEGATIVE PE ASE SEQUENCE BOOSTER EOR UNBALANCED LINES Filed Deb. 11. 1922 INVENTOR G/mr/es L e6. F5r fescue.

ATTORNEY WITNESSES:

Patented Aug. 25, 1925.

155mm ENT OFFICEQ CHARLES LE G. FORTESCUE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WEST- INGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

NEGATIVE-EHASE-SEQUENCE BOOSTER FOR UNBALANCED LINES.

Application iiled December 11, 1922. Serial Nb. 606,143.

To all whom itma z concern:

Be it known that 1, CHARLES Ln G. FORTES- con, a subject of the King of Great Britain, and a resident of Pittsburgh, in the 5 countykof Allegheny and'State of Pennsylvania, have invented a new and useful Improvement in Negative-Phase-Sequence Boosters for Unbalanced Lines, of which the following is a specification. 7 My invention relates to a booster system particularly adapted for long transmission lines supplying unbalanced loads, whereby the unbalanced voltage drops in the lines produce unbalanced voltages at the load points. My invention relates to booster .means for balancing the voltages of a line while permitting the flow of the unbalanced load currents. a v The specific details of my invention will be described and claimed in the following specification, having reference to the accompanying drawing, wherein,

Figure 1 is a diagrammatic view of apparatus and circuits embodying my invention in a system utilizin a dynamo-electric booster driven backwar ly under such conditions that negative-phase-sequence currents are permitted to flow therethrough and the negative-phase-sequence voltages generated therein are substantially equal and opposite to the negative-phase-sequence voltage component of the'line.

Fig. 2 is a vector diagram which will be referred to in the explanation of my invention. V

Fig. 3 is a view similar to Fig. 1 but showing a modification employing induction regulators to perform the booster function.

In the drawing is shown a long three phase transmission line 4, supplied from a source 5, and having a plurality of singlephase feeders 6, 7, 8, 9, 10, 11 and 12 connected at different points. It is assumed that the single-phase loads are not balanced, so that there will be a resultant unbalance in the line voltages. At a certain point in the line, for example, where a olyphase feeder 13 is connected, it is desire to cause theline voltages to be balanced while permitting the unbalanced load currents to be supplied by the source 5.

In order to balance in the line, I have shown, in Fig. 1,

roduce the desired voltage a boostermachine 14, having a three-phase pr mary :w1nd1ng15 connected in series-circuit relatlon to the line and having arelatively rotating secondary member illustrated as carrying a combined damper and unidirectional exciting winding 16 which is energized from a small exciter 17. The

booster machine is designed with a very small air gap in order that the magnetic .coupling between the primary and secondary members may be as perfect as possible. The rotor member of the booster 14 is driven at synchronous speed in the back-.

ward direction by any suitable means, illustrated in the'present case as a three-phase synchronous machine 18 having a prlmary windingv 19 connected across j the line and having an exciting winding 20, shown as the stator winding and provided with a commutator cylinder upon which bear two brushes 21 mounted upon a rocking brush holder 22, whereby the angular position of the synchronously rotating rotor member may controlled. While -I have illustrated a synchronous. motor adapted to assume different angular positions relativefto its synchronously rotating magnetic field, in order to vary the torque supplied to the booster, it will be understood that any other motor adapted to operate at synchronous speedand to deliver a variable torque which may be readily controlled, whereby the angular position of the booster rotor may be regulated, may be employed without departing from the broader features of my invention. i

Referring to Fig. 2, if OA represents the negative-phase-sequence line voltage, in phase and magnitude, and if the booster voltage is adjusted to have the same magnitude, the resultant negative-phase-sequence voltage in the line will be balanced only in case the booster voltage is in phase op osition to the component OA. Thus, if A represents the booster voltage, the negative-phase-sequence voltage component in the line is neutralized. If the booster voltage lags behind the phase position it should have, as indicated at A0, a resultant volt other hand, if the booster voltage is in ad- Vance f'o-f the phase osition it should have, as indicated at A0 a resultant negativephase-sequence line voltage 00 will be produced having a component which lags behind the original negative-phase-sequence voltage component of the. line by 90.

It is thus evident that, if the voltage of the booster is maintained at all times equal in magnitude to the negative-phase-sequence line voltage component, the phase position of the booster may then be adjusted until balancedwoltage conditions obtain in the line. Theadjustment may be made by hand or it may be made by automatic electro-responsive apparatus which responds to the relative phase positlons of the resultant n "ativephase-sequence line voltages.

n Fig. '1 is shown a static networlr 23, comprising an auto-transformer 24hav1ng'a mid-tap directly connected to one 01 the conductors (if the line 4 on 'the unbalanced side "of "the booster, that is, the side nearest the source .5. The two terminals of the auto transformer 24 are connected, through a revsis'tor2l5 and a combined resistance and in- .duct'ancedevice 26., respectively, to the'two remaining conductors of theline 4;, thus de- 'riving'a voltage atthe terminals of the auto "transformer which'is proportional, in relative phase and magnitude, to-the negativephase-fsequence line voltage. lVhile I have illustrated one particular form of apparatus for me'asuringthe negative-phass-sequence voltage component, I do not desire to be limited to this or 'to any other particular form of such apparatus, the drawings being intended as symbolic'ot any negative-phase- .sequence measuring system.

"Do measure nega'tive-phase-sequence line voltage, the current traversing the resistor 25, which is in phase with theposit'ive-phasesequence line woltage iIl'that-phase, is balanced against the current traversing the combined resistance and inductance device 26 which is connected across the phase having a positive-pl]ase-sequence voltage lagging 120 behind the voltage acrossthe re sistor 25. The total impedance of the device .26 equals that of the resistor 25, .so that the currentsobtained with equal voltages are equal. The ratio of inductance to resistance inthe device 26 (is such ,thatthe current lags behind'theimpressed voltage. Hence, tor-balanced positive-p11a'se sequenceline Voltages, the currents in thetwo halves of the auto transformer 24 are equal and dis p1aced 120+,60:180 from one'another,

and no'voltage appears across the auto transformer by reason of balanced positive-phasesequence line voltages. "For negative-phase sequence'line voltages, the phase that was lagging will be'l'ea'di'ng, and the auto-transformer currents will be displaced in the' leading'direction 12060=- 6O-. There will thus be a voltage across the auto transformer proportional to the phase and the. magnitude of the negative-phase sequence line volt {LUG- The static network per se constitllifis t he subject-matter oil thespecification and claims of Patent No. 1,535,587, grantedfApril 28, 1925, to Robert D. Evans, on application Serial No. 358,440, filed.Feb.,.13, 1920, and assigned to the lVestinghouse Electric and lVIanufacturing O0.

The excitation of the exciter 17, which controls the voltage of-the. booster .1114, is governed by means of any-regulating-apparatus. indicated symbolically zit-27, whereby the booster voltage is. maintained sub.-

stant-ially equal, in magnitude,, t0ithenegative-phase-sequence line-voltage as measured by the static network 23.

The phase of the booster' voltagc is controlled by deriving m-voltage which is responsive, in phase and? in magnitude, to the resultant negative-p11ase-sequence line, voltage, a' second networln28, similar to the not work 23, being shown for this purpose, Any suitable phase-indicating relay 29 is then employed to indicatecthecomponent of the resultant voltage which-is. in quadrature re.- lation to the original I negative-,phasesequencc voltage of the line, the quadrature relationbeing obtained by interposing achoke coil 30 in series withfone otthe'negativephase-sequence networks, and a resistorfil in series with the other. -Th e--phase-indieating apparatus 29 operates to energize a small regulating motor 32, in the one direction or the other, insaccordance with the phase of the resultant negative-phase-se: quence line voltage, in order to adjust the position of the rotatinghrush holder 22, and hence also adjusting-the torquedelivered to the booster-"12L byit'he synchronousmotor 18, bymeans of any suitable-mechanism, such as a gear mechanis1n'33.- V 1 f In operation,=the'1notor 18 suppliessuch torque to the booster .14 that the booster draws, or permits the flow of, negative: phase-sequence currents of the proper phase and magnitude to supply the negative-phase sequence load currents, while-the l-ine.voltages on the side of the booster remote from the source are substantially balanced. Booste apparatus, such as is shown, may be placedin theline 'atas many points as may be desired in i order :to, restore balancedvoltage conditions at theEseve-ral distributing;

th positive-phase-sequence impedance otthe booster to facilitate :thewi' ol-ta'ge-regal:

nous machine 18'.:. a rheos'tat 34 being shown,

" in theexciting circuit of the synchronous regu machine 18 for this purpose. I

In Fig. 3 is shown a similar system embooster 14, an induction regulator aggregate comprising a pair of polyphase induction ators 35 and 36 which are combined substantially as shown and claimed in my cop ending application, Serial No. 446,416, filed ebruary 19, 1921.

their primary windings energized in parallel across the line f'rom'the balanced side thereof. The secondary members are connected 1n phase opposition m series with the line,

being connected to the several conductors of the line in the reverse phase-sequence, whereby negat1ve-phasesequence voltages are sup- 38 which are adapted to be simultaneously "rocked in opposite directions by means of the right and left-hand worms 39 and 40, which are driven'by a small regulating motor 41, whereby the magnitude of the booster voltage may be varied without "affecting the phase position thereof. The secondary members of the induction regulators are both mounted aipon the same shaft and driven, through suitable gear-and-worm mechanism 42, by a small regulating motor 43, whereby the phase position of the booster voltagema-y varied without affecting the magnitude thereof.

Suit-able devices for deriving the negativephase-sequence line-voltage components on the two sides of the booster are shown at 23 and 28, as in Fig. 1. The small regulating motor 41 for controlling the magnitude of the booster voltage is controlled by means of a relay 44 having a coil 45, energized by the booster voltage in one phase, and an opposing coil 46, energized in accordance with the negative-phase-sequence line-voltage component on the unbalanced side of the booster. While the coil 45 is shown as being connected to one phase only of the booster voltage, it will be understood that a negativehase-sequence voltage network may be emp oyed, if necessary for greater accuracy, in order to eliminate the effects of the positive-phase-sequence voltage drops in the booster mechanism.

The regulating motor 43 which controls the phase position of the booster voltage is controlled, as in Fig. 1, by means of any suitable phase-indicating relay 29, as illustrated. As the operation of the apparatus shown in Fig. 3 is substantially similar to that shown in Fig. 1, no further explanation is believed necessary.

While I have described certain characteristics of my invention in detail, and while I have pointed out certain of the most obvious cise features described, but I intend that the claims shall be construed to cover all modifications which are fairly comprehended by the language-thereof, when read in connection with the prior art,regardless of the details and functions mentioned in the de- 7 scription or illustrated in the drawing. The induction regulators 35 and 36 have I claim as my invention:

1. The combination with a negative-phasesequence polyphase booster adapted to balance the voltages of an unbalanced polyphase line, of means responsive to the magnitude of the negativephase-sequence voltage component on the unbalanced side of the booster for automatically controlling the magnitude of the booster voltage, and means responsive to the relative phases of the negative-phase-sequence voltage components on both sides of the booster for automatically controlling the phase of the booster voltage.

2. The combination with a negative-phasesequence polyphase booster adapted to balance the volt-ages of an unbalanced polyphase line, of electro-responsive means for adjusting the magnitude of the booster voltage to be substantially equal to the magnitude of the negative-phase-sequencevoltage j component of the line, an 'electro-responsive means for adjusting thephase of the booster voltage in substantial opposition to the phase of the negative-phase-sequence line voltage component. i

3. The combination with a polyphase system having positive and negative phasesequence components of a polyphase electrical quantity, of a series booster for substantially neutralizing one of said components, said last-mentioned component having a variable phase characteristic and a variable voltage characteristic, quick-acting means responsive to one of said characteristics for automatically adjusting an electrical quantity in said booster, and means responsive to the other of said characteristics for then adjusting a second quantity in said booster.

4. The combination with a source of polyphase energy, a transmission line and an unbalanced load resolvable into positive and negative phase-sequence components, of a booster comprising a series-connected element for supplying negative-phase-sequence voltages to the line and a parallel-connected element for deriving positive-phase-sequence currents from the line, means responsive to the phase of the negative-phasesequence voltage component at a predetermined point in said line for automatically maintaining the phase of the booster voltage in alignment therewith, and electro-responsive means for adjusting the magnitude of the booster voltage to maintain substantially balanced voltage conditions at said predeten mined point. v

5. The combination with asource polyphase energ a transmission line and an unbalanced load resolvable into positive and negative phase-sequence components, of a booster comprising a synchronous dynamo electric machine having its primary inding connected in series with said line at a predetermined point to balance the voltages at said point, said machine having a unidirectional exciting winding and damping means rotating in synchronism with the negative phase-sequence currents, means for applying a. mechanical torque to said machine, means responsive to the magnitude of the negativephase-sequence line voltage component at the balancer on the sid towards said source for automatically adjusting the excitation of said machine, and means responsive to the line voltage conditions on the opposite side of said machine for automatically adjusting said torque, whereby balanced line voltage conditions are maintained on said opposite side of said machine.

sive means for automatically regulating the booster to substantially balance the line voltages on the side. of the hoosterreniote from the source. i i' 17. The combination with a polypha se source, of a transmittin line, unbalanced load apparatus connected to said line, s aid line having an appreciable impedance ,oaus ing unbalanced line voltages by reason of the unbalanced line currents supplied to load, a negative-phase-sequence booster interposed in said line at a point remote from said source and between said lead and said source, and elect-fOflfiBPODSlYB for automatically regulating the booster to substantially balance the line voltages on the side of the booster remote from. the so ugce.

The combination with a polyphase having positive and negative phase-seqiience voltage components, of a source of energy therefor, unbalance-d load apparatus supplied thereby, a backyvardly running synchronous dynamo+electric booster machine interposed in said line between. said load and saidsouree, a synchronous machine connected across said line on the side of the booster remote from the source, a. torque-transmitting connection between the rotors of the tivo machines, and electro-responsiye means for automatically regulating the booster to Sitlbstantially balance the line voltages on the side of the booster remote the source.

In testimony whereof, I have hereunto subscribed my name thisfith day of her, 1922. R Y i l CHARLES LE G. 

